Transmission Question

[flightmedic]

Okay, I need to figure out my transmisssion. I don't see much in the way of transmission talk here. But I will throw it out there.

When I purchased my truck, the owner said the trans. had +/- 50,000 miles. He did not have paper to substantiate this, but I found no reaseon to doubt him. Well, as I got used to the truck a little more, I noticed it banged going from drive to reverse or vice versa. Before I could get it looked at it, my overdrive unit failed.

I searched my local area for a reputable medium duty trans. shop and came up with a guy who was reccomended. He spent two hours exlpaining what had happened by use of old parts at his shop. His work area was clean and I got a good overall feel from the guy. Took the truck in and he had it back to me w/ a rebuilt trans. My girlfriend picked the truck up and drove it home but she was convinced it was worse than before, (she described the trans. as slipping). Sure enough she was right. Took the truck back in and the owner was less than pleased, but he was punctual in getting the trans. out and replacing the trq. converter. Said there was a broken spraque. Now, after only 1,000 miles it is slipping again, and it is still "banging" between R and D.

So for my questions. #1 is it normal, as the guy says, for the transmission to bang between R and D. Or is there some sort of pressure/modulation thing happening here he is missing. #2 Is the Trq. converter that weak? I have driven the truck gently and not abused it.

Sorry for the long post (again). Any help would be appreciated.

 

[Case500D]

FM,



Just a thought before you have more transmission work done. I would check the u-joints and the rear axle. Banging from R to D and D to R sounds like excessive backlash in the ring and pinion. I think it should range from . 003" to . 008". With the milage you are at, it is about time for a set of bearings in the rear end. Might be worh a look. Hope this helps.



Jeremy

 

[cerberusiam]

Don't ya just love diagnosing sounds via the internet? Its such an exact science. If we have the same dedinitons in mind a thump between R and D is not unusual and will be more pronounced if the idle is high or the trans is worn. A rebuilt trans with line pressures turned up will probably exibit a thump when reversing directions, with stock pressures it will not be as noticeable. A bang, sharp crack, or a metallic ring is not a good thing and should be investigated immediately. Drive line ujoints or rear end could be a cause for all the above. The slipping trans is not a good sign if it is noticeable and it sounds like you can tell the difference from the last time it had a problem.



Yes the stock converters are junk and if your spending that much money on rebuilds a better tighter converter is a good investment. The fact you found somebody willing to work on the trans is a good thing, the fact it is still exhibiting problems is not so good. There is a reason why most shops won't touch an auto behind the Cummins and the ones that do sometimes don't know all the tricks. The trans can be built to work very well. Don't give up and good luck.

 

[Greenleaf]

Yep'er,

I hear a definite "thud" when shifting from N to Drive and Reverse. Can also see the truck pitch to the side when shifting into a go gear.



The idle speed and the trans shift cable will have a profound effect on how the trans shifts into a gear.



Scott

 

[bgilbert]

Well this is exactly how the uninformed get taken. Both of your problems probly could have been taken care of here in the TDR with your original transmission. My 91 doesnt make a bang when changing directions, so I know it can be fixed. As far as you losing OD, I'm not experienced in that area, but I know its been beaten to death here in TDR land. Most likely a dirty TPS -throttle position sensor. I imagine theres been many trannies rebuilt or replaced just because of a dirty TPS. Different trans installed and worse or the same condition. Or the transmission shop cleans or replaces the TPS along with selling you a rebuilt transmission. ? Anyone? Bill

 

[phillips5]

If the last ownor had put a tighter converter in and now you have it bebuilt and a stock converter installed than you will think the trans is slipping. The stock converters are horable. The engine will go to 1800 or so ond the truck will catch up later.

 

[hdm48]

Hummm, well, it all the rest of the rig checks out and you KNOW it is coming from the transmission,,

excessive clearence in the rear clutch pack,

static adjustment for the K/D rod,

too tight of a rear band adjustment,

too high/low fluid level,

too thick fluid,

too high line pressure,

Too high idle setting,

Bad motor mount,



These are a few of the things I would check out.



Dave